;Exercise 1.12
;The following pattern of numbers is called Pascal’s triangle.
;        1
;      1   1
;    1   2   1
;  1   3   3   1
;1   4   6   4   1
;The numbers at the edge of the triangle are all 1, and each number inside the
;triangle is the sum of the two numbers above it. Write a procedure that
;computes elements of Pascal’s triangle by means of a recursive process.

(define (pascal n k)
  (cond ((or (< k 0) (< n k)) "Parâmetros incorretos")
        ((or (= k 0) (= n k)) 1)
        (else (+ (pascal (- n 1) (- k 1)) (pascal (- n 1) k)))))
